Problem with GPT drive on Ubuntu GNOME Remix 12.10

[quantenmetz]

Hey,

well, I started a "deep scan" with testdisk... It seems to find quite some inconsitencies.
I don't know what is the best way to proceed here. I just want a clean partition table matching the current data layout Windows believes to see (1 3TB NTFS partition) WITHOUT losing the data on the drive.

How do I get there?

Cheers

Q.

[oldfred]

To me all the inconsistencies are scary, I would would backup everything. Any time there are issues there is no guarantee that you will not lose data.

Are you able to know exact sectors of start and end of gpt table?
One of the repairs procedures on the gdisk site was remove partitions and then reset to correct size. As long as you do not reformat and do not change size, data is still there. But if locations with file tables get overwritten or changed then you lose data, so always some risk.

[quantenmetz]

Ok, thanks... but how exactly would I go on?

Backing up will take ages ofc, but I guess that I can do tomorrow. Can't I somehow back up my partitition table data that I have now to be able to switch back to the broken status quo in case of major catastrophe?

I know that the NTFS partition is supposed to start at block 2048, and the last sector should be the last of the drive I guess. Isn't this information sufficient to get a valid GPT table without thrashing my data?

Cheers

Q.

[oldfred]

While gdisk complained, can you use the advanced features of gdisk?

http://www.rodsbooks.com/gdisk/

http://www.rodsbooks.com/gdisk/repairing.html

http://ubuntuforums.org/showthread.php?t=1956173

[quantenmetz]

Hey,

I'm running around in circles. I used gdisk and testdisk extensively, tried all sorts of backup and repair functions. Basically, the partitition table was a mess, the backup was "corrupted", I had "wrong number of bytes per sector" warnings from testdisk flying around ...

In the end I got bold and noted down the sectors of the existing partitions and backups, deleted the partitions with gdisk and created a fresh GPT with gdisk. I played around with new partitions.

Now it gets interesting: I created a new GPT partition (Microsoft Basic Data) matching the starting sector of what I noted down from the Windows-readable, but Ubuntu-unusable initial setup. This lead to a fully readable NTFS partition in Ubuntu with my actual data present, with gdisk, parted and testdisk reporting a valid structure.

Of course, this is exactly where the joy ended: The drive is not redable under Windows anymore, the partitioning tool tells me it is unitialized and wants to create a new GPT table. WARGH!!!!! Now I have the same problem reversed! How can I get a valid setup that even Windows understands? Do I have to create some secret MS-compatible system partition at the beginning of the drive or something? I noticed there are roughly 120 MB of free space (in the partitioning that Windows7 did "for" me)...


Cheers

Q.

[oldfred]

I have not seen a lot of users with 3TB drives but I do not remember anyone else with this type of issue.

Is NTFS partition formatted as NTFS with testdisk? Or is it just created by gdisk and not formatted?

I know testdisk creates XP type NTFS partitions with BIOS and Windows has a different type of NTFS partition for Vista/7. The boot sectors are different as the XP type says to boot with ntldr and Vista/7 says use bootmgr and some other internal details (even if not a boot partition).
But XP does not even work with gpt so is that part of the issue?

I do not have a NTFS partition in my gpt drives, but can you use testdisk and get to this screen and use the dump command. I had used a Windows 7 repair flash drive to fix my XP install and it created a Windows 7 PBR. I had to scroll to the bottom of the PBR but could see the text ntldr in my backup and bootmgr in the "new" PBR. I then recovered back to XP PBR.

Second screen is top of PBR, but you need to scroll down to bottom to see the text. I did not save that page.

[quantenmetz]

well... I'm giving up.

I spent days on this now and I am at a loss.

• Whenever I let Windows 7 64bit 'initialize' the drive, it works under Windows but gdisk reports GPT not present and testdisk says Bad GPT partition, invalid signature.
• When I create the table by hand with gdisk and set the start sector to the correct starting sector of my once-working NTFS partition, I can read the data from Linux but Windows tells me I have to initialize the drive.

It's a ******* circle. I did some reading on what Windows expects from a GPT drive, and apparently there HAS TO BE a Microsoft Reserved partition (MSR) of 128 MB present (which perfectly matches the empty space before the NTFS partition, ...). But also creating this by hand does not help Windows to read the damn thing. And in any case, if the GPT information Win7 creates when "initializing" the drive is NOT EVEN READABLE by any of the tools under Linux, something is foul.

[quantenmetz]

Hmm.... there is one more piece of information that I have been ignoring so far... but I can't make sense of it:

Whenever I use testdisk, regardless of the current state of the GPT table, as soon as I enter the quicksearch utility it keeps finding a NTFS and a Ext4 partition, corresponding to my very first partitioning attempt from gparted (and with wrong starting sectors...).

Where does this information come from??? It keeps finding these two partitions , regardless if I delete the GPT info, blank out MBR, --zap the GPT stuff, create new tables ... Could this be the root of all evil?

Cheers

Q.

PS: All the help is very much appreciated, even though my appreciation might be well-hidden under a pile of frustration right now...

[oldfred]

I do not know if that is an issue with Windows. Testdisk finds old deleted partitions to let you recover them, sometimes. Once repartitioned, the deleted partitions should not be seen by any operating system or most partition tools.

I thought the MSR was only required with bootable systems, not just a data partition.

There are also some new gpt partition internal type IDs.
New code for NTFS gpt partition
http://ubuntuforums.org/showthread.php?t=1822452


Microsoft suggested partitions including reserved partition for gpt & UEFI:
http://technet.microsoft.com/en-us/l...8WS.10%29.aspx
Older Windows info on gpt - 2008 updated 2011
http://msdn.microsoft.com/en-us/wind.../gg463525.aspx
Windows technical info on gpt and GUIDs
http://msdn.microsoft.com/library/wi...sktop/aa365449
Order on drive is important:
http://en.wikipedia.org/wiki/Microso...rved_Partition

[michel30]

This looks like similar to this: read and weep

http://hardforum.com/showthread.php?t=1632902

So you might want to update to the latest version of Intel Rapid Storage Technology driver